Synthesis gas is composed primarily of hydrogen and carbon monoxide. Generally, the H.sub.2 /CO molar ratio is from about 0.6 to 6. The production of synthesis gas from light hydrocarbons such as methane and natural gas by partial oxidation is known. The present invention describes an electrochemical reactor having a solid multi-component membrane, which facilitates the electrocatalytic conversion of light hydrocarbons to synthesis gas.
Numerous publications describe conventional fuel cells which completely oxidize methane to carbon dioxide and water. These fuel cells are not designed to conduct chemical processes, but rather-to generate electricity from fuel gas and air (or oxygen). The processes conducted in fuel cells are selected for complete combustion rather than partial combustion and require completion of an external electric circuit for oxidation of fuel gas to proceed.
Other uses for the electrochemical reactor of the present invention include the partial oxidation of hydrocarbons to form olefins, the partial oxidation of ethane, substitution of aromatic compounds, extraction of oxygen from one or more oxygen-containing gases such as SO.sub.2, SO.sub.3, N.sub.2 O, NO, NO.sub.2, steam, CO.sub.2, ammoxidation of methane, etc.
Dehydrogenation processes for the conversion of saturated organic compounds to unsaturated compounds are well known. Continued efforts have been made in recent years to improve such processes in order to improve the conversion rate and selectivity to desired products. The present invention describes a continuous process for dehydrogenation of saturated hydrocarbons such as ethane to ethylene and acetylene, and propane to propene and propyne. In this process of the present invention, water is a by-product, and electricity may be generated.
The commercial ethane dehydrogenation process, which is an equilibrium limited thermal reaction, must rely on the use of high reaction temperatures to obtain reasonable per pass yields of ethylene. As a result of the high temperatures required, rates of competing cracking and coking reactions are high enough to adversely affect product selectivities.
Convent onal oxydehydrogenation processes, which are not inherently equilibrium limited, also suffer from poor product selectivities at high ethane conversions.
The present invention overcomes the disadvantages inherent in the prior art processes in order to achieve high conversion to unsaturated hydrocarbons combined with low rates of competing cracking and coking reactions.
Processes for the substitution of aromatic compounds are well known. Continued efforts have been made in recent years to improve such processes in order to improve the conversion rate and selectivity to desired products. The present invention describes a continuous process for the substitution of aromatic compounds such as benzene, with a second hydrogen-containing compound. In this process of the present invention, water is a by-product, and electricity can be generated.
Sulfur and nitrogen oxides, for example, are well known noxious pollutants in gas streams emanating from stationary and mobile sources such as power plants, automobiles, ships, trains, etc. Sulfur oxides are known to combine with water vapor to form a highly corrosive vapor causing irritation to eyes and mucous membrane, damage to metal-containing structures, and environmental harm to vegetation due to acid rain. Nitrogen oxides are toxic irritants and are also damaging to the environment. Carbonyl sulfide (COS) is another toxic pollutant formed as a product of a reaction between a sulfur-containing compound and carbon monoxide in a gas stream effluent. Regulations on the discharge of these pollutants into the atmosphere have become increasingly stringent. The present invention describes an electrocatalytic process and electrochemical cell for removing sulfur and nitrogen oxides from gas streams which utilize the chemical driving force of a fuel gas.